A twisted pro-incest campaigner is facing jail over his sick cartoon pictures of Bart Simpson having sex with his sister Lisa and mother Marge.

Andrew Smith told a court the images were legitimate research for a book he was writing on the intimacy of incest - which he said was “a wonderful, expressive thing”.

The 55-year-old was found with other images showing Bart having sex with his teacher Mrs Krabappel and his best pal Millhouse having sex with his own mother.

Smith, a full-time carer for his 87-year-old mother, was convicted at Carlisle Crown Court on nine counts of possessing prohibited images, all cartoons, sketches, drawings or CGIs.

In a bizarre statement to the court, Smith said he wanted to promote ‘the enjoyment of sex and loving relationships within families'.

Smith, from Kendal, Cumbria, was found guilty of nine counts of possessing prohibited images of children as young as eight, after 36 sketches, drawings, cartoons and computer-generated images, many depicting sexual relationships between children and older relatives, were found on disks at his home.

He claimed the images were legitimate ‘research’ for a book he planned to write explaining why incest should be made legal.

The depictions included sexual scenes between relatives, including characters from cartoons such as The Simpsons and King of the Hill.

Smith also told the court his ‘campaign’ included lowering the age of consent for sex to 12 for boys and that a relationship between a 65-year-old man and his 12-year-old granddaughter would be acceptable ‘as long as she wanted it’.

Smith denied using the images for sexual gratification or having a sexual interest in ‘pre-pubescent’ children, saying: “I hate them. I’d machine gun them all.”

Recorder Simon Medland QC branded the images ‘filthy, obscene and very disturbing’, telling Smith he should ‘expect imprisonment’ later this month.